摘要
【目的】铁氧化物是水稻土中活性较高、最常见的氧化物之一,其形态易随着环境的变化而转变。水稻土中水分条件和有机质含量是影响铁氧化物转化的两个重要因素,探究土壤水分条件变化和外源活性有机碳添加条件下水稻土铁氧化物的形态变化,旨在加深对水稻土铁循环的理解。【方法】采用室内培养试验,供试水稻土采自辽宁省沈阳市沈河区。试验设置干湿交替(AWD)、持续淹水(F)和落干(FC)3种水分条件,每个水分条件下设置添加葡萄糖(+C)和不添加葡萄糖(−C)两个处理,在黑暗条件下25℃恒温培养80天。取样测定了土壤铁还原率、游离态氧化铁、络合态氧化铁、无定形态氧化铁含量,以及土壤pH和氧化还原电位(Eh)。【结果】培养80天后,土壤中无定形铁含量在持续淹水条件下增幅最大,不添加和添加葡萄糖处理分别比培养初始期增加了1.16g/kg和1.33 g/kg;在干湿交替和落干条件下,不添加葡萄糖处理的游离态铁含量分别较培养初期增长了20.57%和15.90%;在干湿交替、持续淹水、落干条件下,添加葡萄糖处理的络合态铁含量均有所增加,增幅分别为68.66%、16.09%、17.89%。土壤Eh与无定形铁、络合铁含量呈极显著负相关,与游离铁含量呈显著正相关。【结论】外源活性有机碳的添加促进了铁氧化物的络合,在干湿交替条件下,铁的络合度显著增加了75%。淹水降低土壤Eh,有利于游离态铁向络合态和无定形态转化,提高铁的活性。不论是否添加外源碳,淹水条件下土壤铁的活化度均较高,分别达到0.46和0.47。反复干湿交替促进土壤中非结晶态铁氧化物向结晶态转变,落干再淹水可显著提高铁还原率,添加外源活性有机碳后铁还原率提升更为显著,有利于提高土壤中有效铁含量。
【Objectives】Iron oxides are active and wildly exist in paddy soil,and their forms are easy to conversed with environmental conditions such as water and organic matter content.Therefore,we simulated different water conditions and organic carbon contents in soil,and observed the conversion within iron oxide forms for better understanding of the chemical procession.【Methods】A indoor incubation experiment was carried out using rice soil collected in Shenyang City,Liaoning Province.Three simulated water conditions included alternating dry and wet(AWD),flooding(F),and dry(FC);glucose used as active organic carbon source,was added(+C)or not added(−C)under each water condition to compose 6 treatments in total.All the treatment soils were incubated in the dark at 25℃for 80 days.Soil samples were collected for determining iron reduction rate,the content of iron oxide in free,amorphous and complexed forms,and soil pH,oxidation-reduction potential(Eh).【Results】At the end of incubation,F treatment was recorded the highest increase in amorphous iron content,and the increment were 1.16 g/kg under−C and 1.33 g/kg under+C addition;AWD and FC treatment increased free iron content by 20.57%and 15.90%under−C,respectively;AWD,F and FC treatment increased complexed iron by 68.66%,16.09%and 17.89%under+C,respectively,compared to the initial soil.Amorphous and complexed iron contents were negatively correlated with soil Eh(P<0.01),and free iron content was positively correlated with Eh(P<0.05).【Conclusions】The addition of active organic carbon is conducive to promote the complexation of iron oxides,and the complexation could be increased by 75%under AWD condition.Flooding condition reduces soil Eh,that promoted the transformation of free iron oxide to complexed and amorphous form,and thereby increases the activity of iron.Regardless of adding active organic carbon or not,the activation of iron under flooding condition is higher,reaching 0.46 and 0.47,respectively.Repeated drying and wetting stimulates transition
作者
张景雯
徐嘉欣
兰炫樟
高晓丹
张广才
张昀
ZHANG Jing-wen;XU Jia-xin;LAN Xuan-zhang;GAO Xiao-dan;ZHANG Guang-cai;ZHANG Yun(College of Land and Environment,Shenyang Agricultural University/Key Laboratory of Arable Land Conservation(Northeast China)of Ministry of Agriculture and Rural Affairs,Shenyang,Liaoning 110866,China;Liaoning Agricultural Vocational and Technical College,Yingkou,Liaoning 115009,China)
出处
《植物营养与肥料学报》
CAS
CSCD
北大核心
2024年第11期2093-2103,共11页
Journal of Plant Nutrition and Fertilizers
基金
辽宁省自然科学基金项目(LJKZ0666)
国家重点研发计划子课题(2023YFD150120504)。
关键词
水稻土
铁氧化物形态
水分条件
活性有机碳
铁活化
paddy soil
iron oxide form
water condition
active organic carbon
iron activation
